This invention relates to torque absorbing device for tubular members, specifically to devices for absorbing torsional shocks on tubular members used in drilling operations.
In the process of rotary drilling of wells, abnormal torque can cause stress on the drill string members which comprise the drill string assembly. Repetitive torque overload caused by a variety of phenomenon can cause failure of the drill string assembly. Excessive down hole torque has long been associated with bit-failure and drill string failure.
The present invention provides a torque-shock absorbing tool that will reduce or eliminate abnormal torque from being transmitted through the drill string, yet permit normal torque required for normal drilling operations to be imparted to the drill bit or other down-hole tool. The present invention provides a tool which acts intermediate the drill string and the bottom-hole-assembly (BHA) or bit to absorb abnormal rotation of the drill string (as from bit whirl). The present invention thereby permits normal operation to continue while allowing the use of jars, accelerators, and bumper subs with the tool in place. The invention may also be used as the drive section or portion of such tools without changing the use or operation of the tools.
The tool consists of a mandrel connected to the drill string and attached through an intermediate assembly to the lower sub assembly which both absorbs abnormal torque in the drill string.
If the source of the abnormal torque originates above the tool, the mandrel is helically compressed against a drive cylinder which allows continued rotational movement, while simultaneously absorbing (through both mechanical and hydraulic means) the abnormal torque.
If the source of the abnormal torque originates below the tool, the energy is transmitted to the torque absorber which drives the compression cylinder up, causing compression of the Belleville spring assembly, which in turn move the compression mandrel against the torque sleeve, a hydraulic and mechanical energy absorbing means in the drive cylinder. The dampening effect of the present invention from both directions and independent of the rotational energy which may be continued to be imparted the drill string realizes the long-desired but unobtained goal of a device which absorbs abnormal torque, but continues to provide rotational energy which is required to maintain movement of the drill bit on the well bottom.
An additional object of this tool is to provide a tool for use with polycrystalline diamond compact bits in which the torque-arresting means will address bit whirl, both clockwise and counterclockwise.
A still further object of this tool is to provide a tool in which the tool has means to snub the tool both up and down to permit the tool""s use with bumper subs, jars and accelerators, as needed.
Another related object of this tool is to provide a tool which, in the event that it is necessary to jar the drill-string, the shock tool will home out in both the up and down mode so as not to lessen the jar effect.
Another object of this tool is to provide a tool which will absorb abnormal torque in the drill string to provide the elimination of excessive torque on drill string joints, which will lessen the need for excessive force in loosening joints upon recovery of the well string.
Other objects and advantages of the tool will become apparent from a consideration of the following description and the drawings.